As a rule, media prefers the word ‘teen’ regardless of the crime.
14 must not qualify as a teen, hence “young black male.” I am sure they want to use the term “young black boy” but the words black and boy do not mix.
The media uses "black teen" when one gets shot, to get sympathy from the reader for the "poor boy whose young life was extinguished so soon".
They use "young black male" when one commits a heinous crime, because using "teen" in that context associates the fact that a "black teen" can also be a ruthless, vicious thug, and undercuts the sympathy that the public might feel for "teens" when one gets shot.